Can gesture help? Investigating the potential for transfer in the L2M2 acquisition of a sign language

Gesture has been shown to serve as a substrate for learning a sign language as a second language in a second modality (L2M2). Evidence comes from the perception of signs and their iconicity but also from production, where the accuracy with which hearing learners of a sign language can produce the parameters of a sign is affected by form resemblance between sign and silent gesture. Our study delves deeper into the relationship between gesture and sign in L2M2 acquisition by jointly investigating the lexical and sublexical (i.e. phonological parameter) effects of (i) form resemblance between gesture and sign and (ii) iconicity on the early acquisition of DGS (German Sign Language, Deutsche Gebärdensprache ). In a sign repetition task, participants were shown DGS signs which systematically differed in the degree of form overlap with silent gestures produced for corresponding concepts, as well as in the distribution of similarity over the phonological parameters (handshape, location, movement). After 20 hours of instruction, they repeated this task. Our data show that production accuracy increases across parameters following exposure to DGS. The effects of gesture-sign overlap and sign iconicity are mediated by parameter type, and highlight the importance of considering these two factors on the sublexical in addition to the lexical level. Finally, we suggest that the holistic nature of gesture plays a unique role in gesture-to-sign phonological acquisition, by providing learners only with phonetic, not phonological, information to build phonological categories from, reducing the potential for transfer here.